Conventionally, there are techniques relating to a data storage library, such as the ones described in Patent Documents 1 to 6 mentioned later for instance. The technique described in Patent Document 1 is one for, as to multiple accessors moving on a common rail, controlling the accessor based on flag information indicating operational states of other accessors. The technique in Patent Document 2 is the for, as to the multiple accessors moving on the common rail, writing information on their respective destinations to storage portions recognizable from their respective control portions so as to prevent a collision between the accessors. The technique in Patent Document 3 is one for operating on the common rail a first medium carrying mechanism moving between a medium cabinet and an auxiliary cabinet and a second medium carrying mechanism moving between the auxiliary cabinet and a recording and reading apparatus.
The technique described in the Patent Document 4 is one for dividing a storage rack for storing magnetic tapes into two and allocating to each of divided areas one robot hand for storing and ejecting the magnetic tape.
The technique in Patent Document 5 is one for providing a medium storage rack of a polygonal post having a rack for storing the medium on each face and rotating on its axis and taking and returning the media from and to the racks on different faces thereof with two medium handling mechanisms.
The technique in Patent Document 6 is one for providing multiple picker mechanisms to one medium handling mechanism so as to simultaneously take out or store multiple media.
[Patent Document 1] Japanese Patent Laid-Open No. 4-023118
[Patent Document 2] Japanese Patent Laid-Open No. 10-255373
[Patent Document 3] Japanese Patent Laid-Open No. 6-251485
[Patent Document 4] Japanese Patent Laid-Open No. 6-052611
[Patent Document 5] Japanese Patent Laid-Open No. 5-036187
[Patent Document 6] Japanese Patent Laid-Open No. 11-039768
As for the techniques in Patent Documents 1 to 3 described above, however, all of them move multiple accessors on a common rail. Therefore, considering the collision between the accessors, a moving range of each accessor on the rail is limited so that it is difficult to carry a recording medium efficiently. In the case where a place for saving the accessor is provided at a rail end in order to avoid the collision, there is an inconvenience that a size of a data storage library housing becomes larger accordingly.
The technique in Patent Document 4 has a predetermined work area for each accessor for the cabinet of the recording medium. Therefore, there is a possibility that, if work concentrates in one area, carrying work may be delayed.
The technique in Patent Document 5 has a configuration in which the cabinet of the polygonal post rotates on its axis between two fixed accessors. Therefore, there is an inconvenience that the recording media capable of being handled simultaneously by both the accessors are limited to those in a predetermined positional relation of the polygonal post such as opposed faces.
The technique in Patent Document 6 can store and eject multiple recording media. It is difficult, however, to render the carrying work more efficient because it cannot simultaneously perform a storage operation and an ejection operation of different recording media.